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Inanna Geography > Natural Hazards > Flashcards

Natural Hazards Flashcards

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1
Q

What is a natural hazard?

A

A natural event that threatens people or has the potential to cause damage, destruction and death.

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2
Q

What are atmospheric hazards?

A

Created in the atmosphere by the weather, by the movement of air and water e.g. tornadoes, snow

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3
Q

What are Geological hazards

A

Created by the movement of the earths tectonic plated or surface rock and soils e.g. earthquakes, landslides

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4
Q

What are the human factors affecting hazard risk?

A

Population density and distribution:
-more people = more potential for disaster
-Pacific ring of fire-90% if worlds earthquakes + 452 volcanos -hundreds millions live here
Level of development in a place:
-how country responds after -wealthy respond quicker
-how much money to prepare, predicting + preparing = cope more

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5
Q

What are the physical factors affecting hazard risk?

A

Frequency:
-more often = more prepared + cope more
-large earthquakes + volcanic eruptions -rare events, surprise people
-floods = regular -people adjust buildings + lives to cope with risk.
Natural factors:
-rock type in earthquake -soft sediment = Larger + longer -more likely to liquefy -buildings collapse, shape of coastline in tsunami -gentle coastline = more damage
Magnitude:
-size of event -massive effect on impact.

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6
Q

What are the management affecting hazard risk?

A

Predict:
-hurricanes identified by satellites then tracked
-some hazards easier to predict than others
-allows government to evacuate if needed
Preparation:
-if well prepared can limit impact of hazardous event
Time:
-when at work, many in office, buildings get trapped
-amount of time hazard lasts
-if asleep unprepared
Prevent:
-prevent damage to buildings
-strict building rules

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7
Q

What’s the crust part of the earth?

A

The outermost layer of the earth

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8
Q

What’s the mantle part of the earth?

A

A layer of rock between the core and crust made of molten rock.

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9
Q

What is the core part of the earth?

A

Dense hot rock at the centre of the earth.

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10
Q

What order do the layers of the earth go?

A

Inside to outside:

  • inner core
  • outer core
  • mantle
  • crust
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11
Q

What are convection currents?

A

As heat rises from the earths core, it sets off convection currents in the mantle. The hot bits rise then drop when they cool.

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12
Q

What’s oceanic crust?

A

Found under the sea, thin (5-10km), but very dense (heavy)

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13
Q

What’s the continental crust?

A

Found under the land, thicker (20-200km), but less dense (not as heavy)

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14
Q

Why do earthquakes happen?

A
  • stresses build up between the plates as one passes another
  • as the plated move past each other, they snag and grind, allowing energy to build up.
  • when the plates move again this energy is released as shock or seismic waves through the earths crust.
  • point at which the earthquake is occurring is called the focus. The point above this on the surface of the earth is called the epicentre
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15
Q

What are the types of volcanos

A

Composite volcano:

  • destructive plate margins
  • steep sides, layers of ash and lava. Magma is viscous and cools quickly
  • very explosive

Shield volcano:
-dome shape, sloping sides. Magma is runny and flows long distances before it cools. Gentle explosions

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16
Q

What are destructive plate margins?

A
  • where oceanic plate meets a continental plate
  • moving towards each other
  • denser oceanic plate is subducted beneath the less dense continental plate
  • as it sinks, it melts and makes Magma called andesite
  • the sinking oceanic plate can stick to the continental plate, pressure builds up against friction causing earthquakes
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17
Q

What are constructive plate margins?

A
  • where two oceanic plates are moving apart from each other
  • new oceanic crust forming constantly in gap created
  • earthquakes are caused by friction as the plates tear apart
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18
Q

What are conservative plate margins?

A
  • as plates slide past each other, friction between them causes earthquakes
  • plates moving in different direction or same direction but different speeds
  • no volcanoes
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19
Q

What is a collision plate margin

A
  • when two continental plates are mov my towards each other
  • the plates are not dense enough to sink into the mantle
  • the plates buckle and form mountains
  • there are powerful earthquakes but no volcanoes.
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20
Q

What was the Nepal earthquake?

A
  • 25th April 2015
  • 7.9 On the Richter scale
  • caused by indo -Australian plate colliding with the Eurasian plate
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21
Q

What are the primary effects of Nepal’s earthquake?

A
  • 8,841 death, -16,000 injured
  • 1 Million made homeless
  • historic buildings + Temples destroyed
  • many modern buildings collapsed
  • 26 Hospitals destroyed + 50% of schools
  • reduced supply of water, food, electricity
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22
Q

What are the secondary effects of the Nepal earthquake?

A
  • triggered avalanche in Mount Everest- 19 died
  • less tourists -tourism proved 1.1 million jobs
  • happened before monsoon season when rice planted -rice is Nepal’s staple diet
  • 2/3 population depend on farming
  • rice seed stores in home was ruined by rubble
  • food shortages
  • income loss
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23
Q

What were the immediate responses of of the Nepal earthquake?

A
  • requested international help
  • uk raised $126 mil to provide emergency aid + start rebuilding worst hit areas
  • temporary shelters
  • provides tents for 225,000 people
  • distributed medical supplies
  • important as monsoon season arrived early, increasing risk of waterborne diseases
  • 315,000 cut off by road
  • Nepal’s mountainous terrain made it hard to reach remote areas -Sherpas used to hike relief supplies
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24
Q

What are the long term responses for Nepal’s earthquake?

A
  • carried our post-disaster needs assessment
  • reported 23 areas needed rebuilding
  • heritage sites reopened in June 2015
  • Mount Everest reopened for tourists in August 2015
  • recovery phase started 6 months later to expand crop productions
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25
Q

What was the l’aquila earthquake?

A
  • April 6th 2009
  • 6.3 On the Richter scale
  • epicentre was 7km northwest of the town
  • Eurasian and African plates being pulled apart
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26
Q

What was the primary effects of the Italy earthquake?

A
  • 308, 1,500 injured
  • 67,500 made youth
  • 10,000-15,000 buildings collapsed
  • churches, medieval buildings + monuments collapsed
  • $11,434 Million damage
  • san Salvatore Million damage
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27
Q

What were the secondary effects for the Italy earthquake?

A
  • aftershocks triggered landslides + rockfalls -caused damage to housing + transport
  • landslide + mudflow caused by burst in main water supply
  • lack of housing means prices + rents increased
  • much of city’s central business district cordoned off due to unsafe buildings
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28
Q

What were immediate responses for the earthquake in Italy?

A
  • hotels provided shelter for 10,000
  • 40,000 tents given out
  • within hour -Red Cross searching for survivors
  • water, hot meals, tents, blankets distributed
  • mortgages, bills suspended
  • post office offered free mobile calls
  • declared state of emergency
  • had help from eu
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29
Q

Why the the earthquakes different?

A
  • Nepal had bad government -unprepared -told other countries not to help even though needed help
  • Nepal is poorer -searching teams, less money for medical care, education people about earthquakes, less money for repairs
  • type of plate boundary
  • Italy’s buildings might be more stable than Nepal’s -have more to improve them /earthquake proof them
  • Nepal -poorer quality buildings -collapsed quicker
30
Q

what are some social reasons for why people continue to live in hazardous areas?

A
  • some places well prepared so feel safe

- people worship accent spirits + believe they will warn them of an eruption e.g people in mount merapi in Indonesia.

31
Q

What are some economic reasons for why people continue to live in a hazardous area?

A
  • tourism provides jobs e.g. mount versuvius

- large settlements in seismic zones offer job opportunities e.g San Francisco

32
Q

What are some environmental reasons for why people continue to live in hazardous areas?

A
  • volcanic soils are fertile

- basalt found in volcanic areas can be used in construction and to build roads

33
Q

What is monitoring + how Does it reduce the risk of tectonic hazards?

A
  • using scientific equipment to monitor the earth
  • boreholes -measure water temp, temp increases the closer the magma is t the surface l
  • tilt-meters detect when the volcanoes ww like up we it fills with magma
  • seismometers monitor earths tremors
  • mount St. Helens -bulge on side of mountain
34
Q

What is prediction and how to it reduce the risk from tectonic hazards?

A

-using historical info to predict when + where
-uses historical records and monitoring to predict
-italy constantly looking at historical info like
Turkey and la also do this

35
Q

What is protection and how does it reduce the risk of tectonic hazard?

A
  • designing + building structures to withstand the impact
  • shock absorber built into the cross bracing prevent shaking
  • damper in the roof -acts as a pendulum to counteract shaking of building
  • gas supplies automatically turn off to reduce risk of fires
  • japan 2011 used things like shock absorbers
36
Q

What is planning and how does it reduce the risk of a tectonic hazard?

A
  • people keep emergency kits at home containing water, food, torch, radio
  • earthquake drills practised
  • schools, churches, community centres designated evacuation centres
  • New Zealand well prepared + China
37
Q

How do seismic waves work for monitoring volcanic activity?

A
  • to show if volcano is getting ready to erupt
  • volcanoes experience increasing intensity in frequency and size of earthquake as prepare to erupt
  • monitor using seismometers
  • used in Nevadao del Ruiz
38
Q

How do gas emissions work for monitoring volcanic activity?

A
  • as magma rises into magma chambers gases escape
  • if lots of sulphur gas escape my -signal start of major eruptive sequence
  • in the mount pinatubo volcanic event -amount of sulphur dioxide increased by 10x in 2 weeks
39
Q

How does ground deformation monitor volcanic activity?

A
  • movement of magma within crust can deform the ground above
  • witnessed at yellow stone beneath Yellowstone lake
  • swelling of volcano signals magma has been collected near the surface
  • scientists often measure tilt of slope then track changes
  • mount St. Helens 1980
40
Q

How are satellites images used to monitor volcanic activity?

A
  • use of satellites to detect things about the earths surface
  • it’s useful monitoring changes in volcanoes at surface.
  • using satellites can monitor heat, thermal activity check for swelling magma
  • check for escaping sulphur using gas sensing
  • before + after images
41
Q

How are seismic waves and foreshocks used to monitor earthquakes?

A

-using foreshocks by monitoring seismic waves often get small earthquakes before big one

42
Q

How is animal behaviour used to monitor earthquakes?

A

-animals react to earthquakes before event + before humans

43
Q

How are laser beams used to monitor earthquakes?

A

-can be used to detect plate movement by directing beam across fault line

44
Q

What is weather?

A

The day-to-day condition of the atmosphere.

45
Q

What is climate?

A

The long-term average of weather conditions.

46
Q

What is the general atmospheric circulation model?

A

It shows how wind/air moves around the world. Air circulates in each hemisphere in three cells. The winds are caused by the Sun warming at more intensely at the equator and this warm air moves north, and south to the poles.

47
Q

How does air circulate the earth?

A
  • warm at rises at the equator, travels north and sinks around 30°north. It then travels south back to the equator. This is called the Hadley cell
  • where the air sinks is a high pressure zone -clear skies, warm or cold. Air sinks at the north and South Pole. At areas of high pressure, winds on the group move outwards from these areas
  • where the air is rising is a low pressure zone, lots cloud because warm air rises, cools and condenses to form clouds.
  • air rises at the equator. At areas of low pressure, winds on the ground move towards these areas (to fill space left by rising air)
48
Q

How are tropical storms formed?

A
  1. Sun warms the ocean to 27°C, causing evaporation
  2. The moist warm air rises rapidly, causing low pressure conditions
  3. As the air rises, it cool and condensed, and the rising air draws in more moisture from the ocean, causing strong winds
  4. The Coriolis effect causes the air to spin upwards. Some cooled air sinks back down to create a calm central eye
  5. As the air rises and condenses it forms large, cumulonimbus clouds, which cause heavy rainfall
  6. Air rushes from higher pressure areas outside of the story to lower pressure areas at the centre of the storm creating winds.
49
Q

What conditions are needed for a tropical storm?

A
  • 27°C or more
  • late summer/early autumn
  • 60-70m deep
  • between 5 25° north and south of the equator
50
Q

What happened when typhoon Haiyan hit?

A 
– November 2013 
– category 5 storm hit Phillips 
– Winds of up to 170 mph
–Waves as high as 15 m
Towns affected: 
– Bohol 
- tacloban 
- Panay
51
Q

What were the primary effects of typhoon haiyan?

A
  • around 6300 deaths, most drowned by storm surge m
  • over 600,000 displaced
  • 40,000 homes damaged, 90% tacloban destroyed
  • tacloban airport badly damaged
  • destroyed 30,000 fishing boats
  • strong winds damaged buildings, power lines + destroyed crops
  • over 400mm rain -widespread flooding
52
Q

What were the secondary effects of typhoon haiyan?

A
  • 14million affected -many left homeless
  • flooding causes landslides
  • blocked off roads, cut off remote areas
  • power supplies in some areas cut off for month
  • ferries + airlines disrupted -slowed down aid efforts
  • shortage of water, food, shelter -leaf to outbreaks of disease
  • many jobs lost -hospitals damaged + schools destroyed
  • looting + violence broke out on tacloban
53
Q

What were the immediate responses to typhoon haiyan?

A

– International government + aid agencies responded quickly – food, water, shelters
-helped with search and rescue
– over 1,200 evacuation centres were set up to help the homeless
– UK government sent shelter kits – provided emergency shelter for families
– French, Belgian and israeli field hospitals set up to help injured
– Philippines Red Cross delivered basic food

54
Q

What were the long-term responses to typhoon haiyan?

A

– UN and countries including UK, Australia, Japan, US donated financial aid, supplies and medical support
– Rebuilding of roads, bridges + airport facilities
–‘cost for work’ programmes– People paid to help clear debris + rebuild city
– Foreign donors supported new livelihood opportunities
– Rice farming and fishing quickly re-established
– Aid agencies such as Oxfam supported replacement of fishing marks – vital source of Income
– Homes built away from areas at risk of flooding
– More cyclone shelters built to accommodate people evacuated from coastal areas

55
Q

How can monitoring reduce the effects of tropical storms?

A
  • satellites -cloud pattern associated with tropical storms
  • aircraft -plane flew purposely into hurricane in 1943 -make observations
  • specially equipped aircraft frequently fly into tropical storms -collect air pressure, rainfall, wind speed
56
Q

How can prediction reduce the effects of tropical storms?

A

– Weather data fed into supercomputers
– 1992 location of tropical storm predicted with three days warning
– National hurricane centre predicts storms path and intensity up to 7 days
– 2013 Cyclone phailin successfully predicted
– National hurricane centres around the world issue early warnings so people have time to prepare – some don’t bother

57
Q

How does planning reduce the effects of tropical storms?

A

– Buildings have areas of weaknesses which can be reinforced to reduce damage
– Install hurricane straps between roof and walls
– storm shutters on windows
– emergency generator
– tie down objects
– reinforce garage doors
– Prepare disaster supply kits

58
Q

What were the causes of the Somerset floods?

A

– What is Jan since Records began in 1910

  • succession of depression (areas of low pressure) driven across Atlantic Ocean brought wet weather
  • several weeks rainfall (350mm) - 100mm above average
  • high tides + storm surge swept water up river- spilled over river banks
  • rivers not been dredged for 20 years -became clogged with sediment
59
Q

What were the social impacts of the Somerset floods?

A
  • over 600 houses flooded
  • 16 farms evacuated
  • residents evacuated to temporary accommodation -several months
  • villages cut off -moorland, muchelney -affected people’s daily lives
  • power supplies cut off
60
Q

What were the economic impacts of the Somerset floods?

A
  • flood damage cost more than £10 million
  • over 14,000 vectors of agricultural land under water for 3-4 weeks
  • over 1000 livestock evacuated
  • roads cut off
  • Bristol to Taunton railway line cut off
61
Q

What were the environmental impact of the Somerset floods?

A
  • floodwaters heavily contaminated with sewage + other pollutants -oil and chemicals
  • huge amount of debris has to be cleared
  • stagnant water that had collected for months had to be re oxygenated before being pumped into rivers
62
Q

What was done to reduce the risk of flooding after the Somerset floods?

A
  • £20 million flood action plan launched by Somerset council to reduce risk of future flooding
  • march 2014, 8km of river tone and parratt dredged to increase capacity of river channel
  • road levels raised in places -maintain communications and enable businesses to continue during future flood events
  • vulnerable communities will have flood defences
  • river banks being raised and strengthened + more pumping stations built
63
Q

How do the Milankovitch cycles affect climate change? (Natural causes of climate change)

A

Tilt:
– Earth spins on axis, over a period of 41,000 years, tilt of earths axis moved back + forth
Wobble:
– When it spins it naturally wobbles, describes natural ‘wobble‘, takes 2,600 years
Orbit:
– Every 100,000 years, changes from being almost circular to mildly elliptical, describes path of earth as it orbits the Sun

64
Q

How does solar activity affect climate change? (Natural causes of climate change)

A
  • sunspot - dark patch that appears from time to time on surface of sun
  • over 11 years
  • increases from a minimum to a maximum then back to minimum
  • sum gives off more heat when on maximum
  • solar output reduced when on minimum
65
Q

How does volcanic activity cause climate change? (Natural causes of climate change)

A

– When volcanoes erupt emit ash, gases and liquids

  • volcanic ash can block out the sun -reducing temp of earth
  • sulphuric acid acts like tiny mirrors reflecting radiation from sun
  • when volcanoes erupt they often cool the climate
  • global temps cooled by 0.4-0.7 c when mount tamboura erupted
66
Q

What is climate change?

A

A long term change in the earths climate, especially a change due to an increase in the atmospheric temp.

67
Q

What is the recent evidence for climate change?

A 
Sea levels: 
- rising 
- 45% melting glaciers 
- 38% thermal expansion 
- gone up by 19cm since 1900
Land temp:
- been going up since 1850 
- rapid increases since 1900
-since 1880 increased by 0.5 c
Ice cores:
- drilling down into glaciers to look at the ice
68
Q

What is mitigation?

A

International agreements to recuse greenhouse gas emissions (trying to stop the problem)

69
Q

What is adaptation?

A

Actions taken to adjust to climate change to reduce damage, limit the impacts or cope with the consequence (trying to stop the damage)

70
Q

How are we trying to stop climate change?

A
  1. Alternate energy sources e.g hydroelectricity, nuclear, solar
  2. Carbon capture
  3. Planting trees
  4. International agreements
71
Q

What is carbon capture?

A

Captures CO2, possible to catch and 90%. One captured it’s compressed and transported by pipeline or truck and injected deep underground for storage.

72
Q

How does planting trees (afforestation) help to stop climate change?

A
  • removes co2 from atmosphere

- release moisture which creates cloud -has cooling effect, reduces suns rays that are hitting earth

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